In HSDPA communication, the communication is performed by using HS-PDSCH (High Speed Physical Shared Downlink Channel), as a common channel in which mobile terminals share a code, and timing when a signal is transmitted from a base station by using the HS-PDSCH is peculiar to the base station. For this reason, in the HSDPA communication, it is impossible to transmit same data from a plurality of base stations in synchronization with a timing and perform soft handover in which the data are combined on the side of the mobile terminal. As a result, when it is required to perform the handover because of moving of the mobile terminal during the HSDPA communication, hard handover is performed in which the HSDPA communication with a currently connected base station is disconnected once and then the communication with a next base station is started. Thus, a time period during which the communication is interrupted is generated in the handover. The same process as described above is performed even if the timing of the HSDPA channel is synchronized with each other among base stations so that it is unnecessary that the communication is stopped. Thus, in case that the transmission timing is synchronized with each other among base stations, as in case that a handover is performed between sectors, the same process as described above is performed so that a useless stopping time of the communication is generated, regardless of that it is not necessarily required to stop the communication once.
Here, in a mobile communication system, a method of using reception quality in a mobile terminal as a criterion in selecting a next base station is proposed in Japanese Laid Open Patent Applications (JP-A-Heisei 1-190137 and JP-P2001-238239A). As described above, even in the method of using the reception quality in the mobile terminal as the criterion in selecting the next base station, this useless interruption time is generated.